This application is directed to a reciprocating drive apparatus for converting rotary motion into linear motion, or vice versa.
Reciprocating drives for converting between rotary and linear motion may be used, for example, to drive the piston of a pump in various different types of machine. Air pumps are commonly used for ventilators in the medical field, but there are major challenges inherent in using a reciprocating drive to actuate such pumps. For example, such pumps, which are required to deliver clean air, cannot use lubricants between the piston and cylinder. They must also be sufficiently small to fit into the equipment. This means that any offset from a true linear motion is more critical and can cause side loads which will eventually lead to failure of the pump.
U.S. Pat. No. 5,762,480 describes one reciprocating machine which has been used to drive an air pump. This machine uses a four bar linkage mechanism to convert the rotary motion of the drive motor into a linear movement to operate the pump. This does not deliver a true linear motion, due to the nature of the linkage mechanism, and this results in side load to the seal diaphragms and the pump cylinder or cylinders. This could eventually result in air leakage and component failure.